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Hajishafiee M, Ullrich SS, Fitzgerald PC, Horowitz M, Lange K, Poppitt SD, Feinle-Bisset C. Suppression of Energy Intake by Intragastric l-Tryptophan in Lean and Obese Men: Relations with Appetite Perceptions and Circulating Cholecystokinin and Tryptophan. J Nutr 2021; 151:2932-2941. [PMID: 34255069 DOI: 10.1093/jn/nxab218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 05/16/2021] [Accepted: 06/11/2021] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND l-Tryptophan reduces energy intake in healthy men. The underlying mechanisms, including appetite, plasma cholecystokinin (CCK), tryptophan (Trp), and the ratio of Trp to large neutral amino acids (Trp:LNAAs ratio), and whether responses differ in lean and obese individuals, are uncertain. OBJECTIVES We evaluated the effects of intragastric Trp on energy intake (primary outcome) and their potential mechanisms, pre- and postmeal, in lean men and those with obesity. METHODS Twelve lean men [mean ± SD age: 30 ± 3 y; BMI (in kg/m2): 23 ± 1] and 13 men with obesity (mean ± SD age: 31 ± 3 y; BMI: 33 ± 1) received, on 3 separate occasions, in double-blind, randomized order, 3 g ("Trp-3") or 1.5 g ("Trp-1.5") Trp, or control ("C"), intragastrically, 30 min before a buffet-meal. Energy intake from the buffet-meal, hunger, fullness, and plasma CCK and amino acid concentrations were measured in response to Trp alone and for 2 h postmeal. Data were analyzed using maximum likelihood mixed-effects models, with treatment, group, and treatment-by-group interaction as fixed effects. RESULTS Trp alone increased plasma CCK, Trp, and the Trp:LNAAs ratio (all P < 0.001), with no difference between groups. Trp suppressed energy intake (P < 0.001), with no difference between groups (lean, C: 1085 ± 102 kcal, Trp-1.5: 1009 ± 92 kcal, Trp-3: 868 ± 104 kcal; obese, C: 1249 ± 98 kcal, Trp-1.5: 1217 ± 90 kcal, Trp-3: 1012 ± 100 kcal). Postmeal, fullness was greater after Trp-3 than after C and Trp-1.5 (all P < 0.05), and in men with obesity than in lean men (P < 0.05). Plasma Trp and the Trp:LNAAs ratio were greater after Trp-3 and Trp-1.5 than after C (all P < 0.001), and tended to be less in men with obesity than in the lean (P = 0.07) (Trp:LNAAs ratio: lean, C: 1.5 ± 0.2, Trp-1.5: 6.9 ± 0.7, Trp-3: 10.7 ± 1.4; obese, C: 1.4 ± 0.1, Trp-1.5: 4.6 ± 0.7, Trp-3: 7.8 ± 1.3). There were inverse correlations of energy intake with plasma Trp and the Trp:LNAAs ratio in both groups (lean, both r = -0.50, P < 0.01; obese, both r = -0.40, P < 0.05). CONCLUSIONS Intragastric Trp has potent energy intake-suppressant effects, in both lean men and those with obesity, apparently related to the Trp:LNAAs ratio.
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Affiliation(s)
- Maryam Hajishafiee
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, South Australia, Australia
| | | | - Penelope Ce Fitzgerald
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, South Australia, Australia
| | - Michael Horowitz
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, South Australia, Australia
- Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Kylie Lange
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, South Australia, Australia
| | - Sally D Poppitt
- Human Nutrition Unit, School of Biological Sciences, Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Christine Feinle-Bisset
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, South Australia, Australia
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Elovaris RA, Bitarafan V, Agah S, Ullrich SS, Lange K, Horowitz M, Feinle-Bisset C. Comparative Effects of the Branched-Chain Amino Acids, Leucine, Isoleucine and Valine, on Gastric Emptying, Plasma Glucose, C-Peptide and Glucagon in Healthy Men. Nutrients 2021; 13:nu13051613. [PMID: 34064996 PMCID: PMC8150294 DOI: 10.3390/nu13051613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/22/2021] [Accepted: 04/29/2021] [Indexed: 02/04/2023] Open
Abstract
(1) Background: Whey protein lowers postprandial blood glucose in health and type 2 diabetes, by stimulating insulin and incretin hormone secretion and slowing gastric emptying. The branched-chain amino acids, leucine, isoleucine and valine, abundant in whey, may mediate the glucoregulatory effects of whey. We investigated the comparative effects of intragastric administration of leucine, isoleucine and valine on the plasma glucose, C-peptide and glucagon responses to and gastric emptying of a mixed-nutrient drink in healthy men. (2) Methods: 15 healthy men (27 ± 3 y) received, on four separate occasions, in double-blind, randomised fashion, either 10 g of leucine, 10 g of isoleucine, 10 g of valine or control, intragastrically, 30 min before a mixed-nutrient drink. Plasma glucose, C-peptide and glucagon concentrations were measured before, and for 2 h following, the drink. Gastric emptying of the drink was quantified using 13C-acetate breath-testing. (3) Results: Amino acids alone did not affect plasma glucose or C-peptide, while isoleucine and valine, but not leucine, stimulated glucagon (p < 0.05), compared with control. After the drink, isoleucine and leucine reduced peak plasma glucose compared with both control and valine (all p < 0.05). Neither amino acid affected early (t = 0–30 min) postprandial C-peptide or glucagon. While there was no effect on overall gastric emptying, plasma glucose at t = 30 min correlated with early gastric emptying (p < 0.05). (4) Conclusion: In healthy individuals, leucine and isoleucine lower postprandial blood glucose, at least in part by slowing gastric emptying, while valine does not appear to have an effect, possibly due to glucagon stimulation.
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Affiliation(s)
- Rachel A. Elovaris
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide 5005, Australia; (R.A.E.); (V.B.); (S.A.); (K.L.); (M.H.)
| | - Vida Bitarafan
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide 5005, Australia; (R.A.E.); (V.B.); (S.A.); (K.L.); (M.H.)
| | - Shahram Agah
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide 5005, Australia; (R.A.E.); (V.B.); (S.A.); (K.L.); (M.H.)
| | - Sina S. Ullrich
- Clinical Trials Unit, University Hospital Basel, 4031 Basel, Switzerland;
| | - Kylie Lange
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide 5005, Australia; (R.A.E.); (V.B.); (S.A.); (K.L.); (M.H.)
| | - Michael Horowitz
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide 5005, Australia; (R.A.E.); (V.B.); (S.A.); (K.L.); (M.H.)
| | - Christine Feinle-Bisset
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide 5005, Australia; (R.A.E.); (V.B.); (S.A.); (K.L.); (M.H.)
- Correspondence: ; Tel.: +61-8-8313-6053
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Elovaris RA, Hajishafiee M, Ullrich SS, Fitzgerald PCE, Lange K, Horowitz M, Feinle-Bisset C. Intragastric administration of leucine and isoleucine does not reduce the glycaemic response to, or slow gastric emptying of, a carbohydrate-containing drink in type 2 diabetes. Diabetes Res Clin Pract 2021; 171:108618. [PMID: 33310174 DOI: 10.1016/j.diabres.2020.108618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/02/2020] [Accepted: 12/04/2020] [Indexed: 02/07/2023]
Abstract
AIMS In healthy individuals, intragastric administration of the branched-chain amino acids, leucine and isoleucine, diminishes the glycaemic response to a mixed-nutrient drink, apparently by stimulating insulin and slowing gastric emptying, respectively. This study aimed to evaluate the effects of leucine and isoleucine on postprandial glycaemia and gastric emptying in type-2 diabetes mellitus (T2D). METHODS 14 males with T2D received, on 3 separate occasions, in double-blind, randomised fashion, either 10 g leucine, 10 g isoleucine or control, intragastrically 30 min before a mixed-nutrient drink (500 kcal; 74 g carbohydrates, 18 g protein, 15 g fat). Plasma glucose, insulin and glucagon were measured from 30 min pre- until 120 min post-drink. Gastric emptying of the drink was also measured. RESULTS Leucine and isoleucine stimulated insulin, both before and after the drink (all P < 0.05; peak (mU/L): control: 70 ± 15; leucine: 88 ± 17; isoleucine: 74 ± 15). Isoleucine stimulated (P < 0.05), and leucine tended to stimulate (P = 0.078), glucagon before the drink, and isoleucine stimulated glucagon post-drink (P = 0.031; peak (pg/mL): control: 62 ± 5; leucine: 70 ± 9; isoleucine: 69 ± 6). Neither amino acid affected gastric emptying or plasma glucose (peak (mmol/L): control: 12.0 ± 0.5; leucine: 12.5 ± 0.7; isoleucine: 12.0 ± 0.6). CONCLUSIONS In contrast to health, in T2D, leucine and isoleucine, administered intragastrically in a dose of 10 g, do not lower the glycaemic response to a mixed-nutrient drink. This finding argues against a role for 'preloads' of either leucine or isoleucine in the management of T2D.
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Affiliation(s)
- Rachel A Elovaris
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Maryam Hajishafiee
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Sina S Ullrich
- Department of Clinical Research, University Hospital Basel and University of Basel, Basel, Switzerland
| | - Penelope C E Fitzgerald
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Kylie Lange
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michael Horowitz
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Christine Feinle-Bisset
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia.
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Hajishafiee M, Ullrich SS, Steinert RE, Poppitt SD, Luscombe-Marsh ND, Horowitz M, Feinle-Bisset C. Effects of intragastric tryptophan on acute changes in the plasma tryptophan/large neutral amino acids ratio and relationship with subsequent energy intake in lean and obese men. Food Funct 2020; 11:7095-7103. [PMID: 32729586 DOI: 10.1039/d0fo00773k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Circulating tryptophan/large neutral amino acids (tryptophan/LNAA) ratio, an indicator of brain serotonin levels, may be important in appetite regulation, together with gastrointestinal (gastric emptying, plasma cholecystokinin) mechanisms. We have compared effects of intragastric tryptophan ('Trp') on the plasma tryptophan/LNAA ratio in lean and obese men, and the associations of the tryptophan/LNAA ratio, gastric emptying and CCK concentrations with energy intake. Lean and obese male participants (n = 16 each) received 3 g Trp or volume-matched control intragastrically, 15 min before a mixed-nutrient drink (300 mL, 400 kcal) (t = 0 min) in randomised, double-blind fashion. Plasma amino acid (for calculation of the plasma tryptophan/LNAA ratio) and CCK concentrations were measured from t = -20-60 min. Gastric emptying was assessed from t = 0-60 min, and ad-libitum energy intake from a standardised buffet-style meal from t = 60-90 min. The increase in the plasma tryptophan/LNAA ratio was less in obese, than lean, participants (P < 0.05), and greater in lean participants who reduced their energy intake (by >0 kcal) after Trp compared with those who did not (by ≤0 kcal) (P < 0.05). Moreover, in participants who reduced their energy intake, the ratio was lower in obese, than in lean (P < 0.05). There was a trend for an inverse correlation between energy intake with the plasma tryptophan/LNAA ratio in lean (r = -0.4, P = 0.08), but not in obese, participants. There was no significant difference in gastric emptying or CCK between participants who reduced their energy intake and those who did not. In conclusion, the plasma tryptophan/LNAA ratio appears to be a determinant of the suppression of energy intake in response to tryptophan in normal-weight people, but not in those with obesity. The role of the plasma tryptophan/LNAA ratio to regulate energy intake, and potential changes in obesity, warrant evaluation in prospective studies.
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Affiliation(s)
- Maryam Hajishafiee
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia.
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McVeay C, Steinert RE, Fitzgerald PCE, Ullrich SS, Horowitz M, Feinle-Bisset C. Effects of intraduodenal coadministration of lauric acid and leucine on gut motility, plasma cholecystokinin, and energy intake in healthy men. Am J Physiol Regul Integr Comp Physiol 2020; 318:R790-R798. [PMID: 32160019 DOI: 10.1152/ajpregu.00352.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The fatty acid, lauric acid (C12), and the amino acid, leucine (Leu) stimulate gut hormones, including CCK, associated with suppression of energy intake. In our recent study, intraduodenal infusion of a combination of C12 and l-tryptophan, at loads that individually did not affect energy intake, reduced energy intake substantially, associated with much greater stimulation of CCK. We have now investigated whether combined administration of C12 and Leu would enhance the intake-suppressant effects of each nutrient, when given at loads that each suppress energy intake individually. Sixteen healthy, lean males (age: 23 ± 2 yr) received, in randomized, double-blind fashion, 90-min intraduodenal infusions of control (saline), C12 (0.4 kcal/min), Leu (0.45 kcal/min), or C12+Leu (0.85 kcal/min). Antropyloroduodenal pressures were measured continuously and plasma CCK at 15-min intervals, and energy intake from a standardized buffet-meal, consumed immediately postinfusion, was quantified. All nutrient infusions stimulated plasma CCK compared with control (P < 0.05). Moreover, C12 and C12+Leu stimulated CCK compared with Leu (P < 0.05) (mean concentration, pmol/L; control: 2.3 ± 0.3, C12: 3.8 ± 0.3, Leu: 2.7 ± 0.3, and C12+Leu: 4.0 ± 0.4). C12+Leu, but not C12 or Leu, stimulated pyloric pressures (P < 0.05). C12+Leu and C12 reduced energy intake (P < 0.05), and there was a trend for Leu to reduce (P = 0.06) energy intake compared with control, with no differences between the three nutrient treatments (kcal; control: 1398 ± 84, C12: 1226 ± 80, Leu: 1260 ± 92, and C12+Leu: 1208 ± 83). In conclusion, combination of C12 and Leu, at the loads given, did not reduce energy intake beyond their individual effects, possibly because maximal effects had been evoked.
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Affiliation(s)
- Christina McVeay
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Robert E Steinert
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Penelope C E Fitzgerald
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Sina S Ullrich
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michael Horowitz
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Christine Feinle-Bisset
- Adelaide Medical School and Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
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McVeay C, Fitzgerald PCE, Ullrich SS, Steinert RE, Horowitz M, Feinle-Bisset C. Effects of intraduodenal administration of lauric acid and L-tryptophan, alone and combined, on gut hormones, pyloric pressures, and energy intake in healthy men. Am J Clin Nutr 2019; 109:1335-1343. [PMID: 31051504 DOI: 10.1093/ajcn/nqz020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 01/25/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The fatty acid, lauric acid ('C12'), and the amino acid, L-tryptophan ('Trp'), modulate gastrointestinal functions including gut hormones and pyloric pressures, which are important for the regulation of energy intake, and both potently suppress energy intake. OBJECTIVE We hypothesized that the intraduodenal administration of C12 and Trp, at loads that do not affect energy intake individually, when combined will reduce energy intake, which is associated with greater modulation of gut hormones and pyloric pressures. DESIGN Sixteen healthy, lean males (age: 24 ± 1.5 y) received 90-min intraduodenal infusions of saline (control), C12 (0.3 kcal/min), Trp (0.1 kcal/min), or C12 + Trp (0.4 kcal/min), in a randomized, double-blind, cross-over study. Antropyloroduodenal pressures were measured continuously, and plasma cholecystokinin (CCK), ghrelin, and glucagon-like peptide-1 (GLP-1) concentrations, appetite perceptions, and gastrointestinal symptoms at 15-min intervals. Immediately after the infusions, energy intake from a standardized buffet meal was quantified. RESULTS C12 + Trp markedly reduced energy intake (kcal; control: 1,232 ± 72, C12: 1,180 ± 82, Trp: 1,269 ± 73, C12 + Trp: 1,056 ± 106), stimulated plasma CCK (AUC(area under the curve)0-90 min, pmol/L*min; control: 21 ± 8; C12: 129 ± 15; Trp: 97 ± 16; C12 + Trp: 229 ± 22) and GLP-1 (AUC0-90 min, pmol/L*min; control: 102 ± 41; C12: 522 ± 102; Trp: 198 ± 63; C12 + Trp: 545 ± 138), and suppressed ghrelin (AUC0-90 min, pg/mL*min; control: -3,433 ± 2,647; C12: -11,825 ± 3,521; Trp: -8,417 ± 3,734; C12 + Trp: -18,188 ± 4,165) concentrations, but did not stimulate tonic, or phasic, pyloric pressures, compared with the control (all P < 0.05), or have adverse effects. C12 and Trp each stimulated CCK (P < 0.05), but to a lesser degree than C12 + Trp, and did not suppress energy intake or ghrelin. C12, but not Trp, stimulated GLP-1 (P < 0.05) and phasic pyloric pressures (P < 0.05), compared with the control. CONCLUSION The combined intraduodenal administration of C12 and Trp, at loads that individually do not affect energy intake, substantially reduces energy intake, which is associated with a marked stimulation of CCK and suppression of ghrelin. The study was registered as a clinical trial at the Australian and New Zealand Clinical Trial Registry (www.anzctr.org.au,) as 12613000899741.
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Affiliation(s)
- Christina McVeay
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Penelope C E Fitzgerald
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Sina S Ullrich
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Robert E Steinert
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michael Horowitz
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Christine Feinle-Bisset
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
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Elovaris RA, Fitzgerald PCE, Bitarafan V, Ullrich SS, Horowitz M, Feinle-Bisset C. Intraduodenal Administration of L-Valine Has No Effect on Antropyloroduodenal Pressures, Plasma Cholecystokinin Concentrations or Energy Intake in Healthy, Lean Men. Nutrients 2019; 11:nu11010099. [PMID: 30621276 PMCID: PMC6356499 DOI: 10.3390/nu11010099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/02/2019] [Accepted: 01/03/2019] [Indexed: 02/07/2023] Open
Abstract
Whey protein is rich in the branched-chain amino acids, L-leucine, L-isoleucine and L-valine. Thus, branched-chain amino acids may, at least in part, mediate the effects of whey to reduce energy intake and/or blood glucose. Notably, 10 g of either L-leucine or L-isoleucine, administered intragastrically before a mixed-nutrient drink, lowered postprandial blood glucose, and intraduodenal infusion of L-leucine (at a rate of 0.45 kcal/min, total: 9.9 g) lowered fasting blood glucose and reduced energy intake from a subsequent meal. Whether L-valine affects energy intake, and the gastrointestinal functions involved in the regulation of energy intake, as well as blood glucose, in humans, is currently unknown. We investigated the effects of intraduodenally administered L-valine on antropyloroduodenal pressures, plasma cholecystokinin, blood glucose and energy intake. Twelve healthy lean men (age: 29 ± 2 years, BMI: 22.5 ± 0.7 kg/m²) were studied on 3 separate occasions in randomised, double-blind order. Antropyloroduodenal pressures, plasma cholecystokinin, blood glucose, appetite perceptions and gastrointestinal symptoms were measured during 90-min intraduodenal infusions of L-valine at 0.15 kcal/min (total: 3.3 g) or 0.45 kcal/min (total: 9.9 g), or 0.9% saline (control). Energy intake from a buffet-meal immediately after the infusions was quantified. L-valine did not affect antral, pyloric (mean number; control: 14 ± 5; L-Val-0.15: 21 ± 9; L-Val-0.45: 11 ± 4), or duodenal pressures, plasma cholecystokinin (mean concentration, pmol/L; control: 3.1 ± 0.3; L-Val-0.15: 3.2 ± 0.3; L-Val-0.45: 3.0 ± 0.3), blood glucose, appetite perceptions, symptoms or energy intake (kcal; control: 1040 ± 73; L-Val-0.15: 1040 ± 81; L-Val-0.45: 1056 ± 100), at either load (p > 0.05 for all). In conclusion, intraduodenal infusion of L-valine, at loads that are moderately (3.3 g) or substantially (9.9 g) above World Health Organization valine requirement recommendations, does not appear to have energy intake- or blood glucose-lowering effects.
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Affiliation(s)
- Rachel A Elovaris
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Penelope C E Fitzgerald
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Vida Bitarafan
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Sina S Ullrich
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Michael Horowitz
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Christine Feinle-Bisset
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
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Ullrich SS, Fitzgerald PCE, Giesbertz P, Steinert RE, Horowitz M, Feinle-Bisset C. Effects of Intragastric Administration of Tryptophan on the Blood Glucose Response to a Nutrient Drink and Energy Intake, in Lean and Obese Men. Nutrients 2018; 10:nu10040463. [PMID: 29642492 PMCID: PMC5946248 DOI: 10.3390/nu10040463] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 02/07/2023] Open
Abstract
Tryptophan stimulates plasma cholecystokinin and pyloric pressures, both of which slow gastric emptying. Gastric emptying regulates postprandial blood glucose. Tryptophan has been reported to decrease energy intake. We investigated the effects of intragastric tryptophan on the glycaemic response to, and gastric emptying of, a mixed-nutrient drink, and subsequent energy intake. Lean and obese participants (n = 16 each) received intragastric infusions of 1.5 g ("Trp-1.5g") or 3.0 g ("Trp-3.0g") tryptophan, or control, and 15 min later consumed a mixed-nutrient drink (56 g carbohydrates). Gastric emptying (13C-acetate breath-test), blood glucose, plasma C-peptide, glucagon, cholecystokinin and tryptophan concentrations were measured (t = 0-60 min). Energy intake was assessed between t = 60-90 min. In lean individuals, Trp-3.0g, but not Trp-1.5g, slowed gastric emptying, reduced C-peptideAUC and increased glucagonAUC (all P < 0.05), but did not significantly decrease the blood glucose response to the drink, stimulate cholecystokinin or reduce mean energy intake, compared with control. In obese individuals, Trp-3.0g, but not Trp-1.5g, tended to slow gastric emptying (P = 0.091), did not affect C-peptideAUC, increased glucagonAUC (P < 0.001) and lowered blood glucose at t = 30 min (P < 0.05), and did not affect cholecystokinin or mean energy intake. In obese individuals, intragastrically administered tryptophan may reduce postprandial blood glucose by slowing gastric emptying; the lack of effect on mean energy intake requires further investigation.
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Affiliation(s)
- Sina S Ullrich
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Penelope C E Fitzgerald
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Pieter Giesbertz
- Department of Nutritional Physiology, Technical University of Munich, Gregor-Mendel Strasse 2, 85354 Freising, Germany.
| | - Robert E Steinert
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
- Department of Surgery, Division of Visceral and Transplantation Surgery, University Hospital Zürich, Rämistrasse 100, 8091 Zürich, Switzerland.
| | - Michael Horowitz
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
| | - Christine Feinle-Bisset
- Adelaide Medical School and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Level 5 Adelaide Health and Medical Sciences Building, Corner North Terrace and George Street, Adelaide 5005, Australia.
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Steinert RE, Ullrich SS, Geary N, Asarian L, Bueter M, Horowitz M, Feinle-Bisset C. Comparative effects of intraduodenal amino acid infusions on food intake and gut hormone release in healthy males. Physiol Rep 2017; 5:e13492. [PMID: 29138359 PMCID: PMC5688783 DOI: 10.14814/phy2.13492] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 10/12/2017] [Indexed: 02/07/2023] Open
Abstract
In contrast to the many studies of the effects of individual amino acids (AAs) on eating, no studies have compared the effects of different AAs on eating and underlying preabsorptive gastrointestinal mechanisms. To compare the effects of intraduodenal infusions of l-tryptophan (TRP), l-leucine (LEU), l-phenylalanine (PHE) and l-glutamine (GLN) on appetite, gastrointestinal hormone responses (including ghrelin, cholecystokinin (CCK), peptide YY (PYY) and glucagon-like peptide-1 [GLP-1]), glycemia (glucagon, insulin and glucose) and test meal size in healthy males, we retrospectively analyzed data from four published independent, randomized, double-blind, placebo-controlled studies of 90-min intraduodenal infusions of the individual AAs. The designs of the studies were identical, except the dose of TRP (0.15 kcal/min) was lower than that of the other AAs (0.45 kcal/min) because higher doses of this AA were not well tolerated. TRP and LEU decreased intake more than PHE (reductions relative to control, ~219 ± 68, ~170 ± 48 and ~12 ± 57 kcal, respectively), and TRP decreased intake more than GLN (~31 ± 82 kcal). These effects of TRP and LEU versus GLN, but not versus PHE, were paralleled by greater decreases in plasma ghrelin, and increases in CCK, concentrations. TRP increased PYY more than GLN or LEU, but not PHE. LEU increased PYY less than PHE. No significant differences were detected for GLP-1. PHE increased glucagon more than TRP or LEU, and increased insulin more than TRP. Under our experimental conditions, intraduodenal TRP and LEU were more satiating than PHE and GLN. The greater satiating efficacy of LEU versus PHE was significantly dissociated from the effects of these AAs on PYY, while the greater satiating potency of TRP versus PHE was significantly dissociated from the effects of these AAs on insulin and glucagon. In contrast, ghrelin and CCK, and potentially other mechanisms, including central sensing of individual AAs, appear to be stronger candidate mechanisms for the relative satiating effects obtained.
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Affiliation(s)
- Robert E Steinert
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- NHMRC Centre of Research Excellence in Translating Nutritional Science to Good Health University of Adelaide, Adelaide, South Australia, Australia
- Department of Surgery, Division of Visceral and Transplantation Surgery, University Hospital Zürich, Zürich, Switzerland
| | - Sina S Ullrich
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- NHMRC Centre of Research Excellence in Translating Nutritional Science to Good Health University of Adelaide, Adelaide, South Australia, Australia
| | - Nori Geary
- Department of Psychiatry, Weill Medical College of Cornell University, New York, New York
| | - Lori Asarian
- Department of Medicine-Immunobiology, Robert Larner College of Medicine University of Vermont, Burlington, Vermont
| | - Marco Bueter
- Department of Surgery, Division of Visceral and Transplantation Surgery, University Hospital Zürich, Zürich, Switzerland
| | - Michael Horowitz
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- NHMRC Centre of Research Excellence in Translating Nutritional Science to Good Health University of Adelaide, Adelaide, South Australia, Australia
| | - Christine Feinle-Bisset
- Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
- NHMRC Centre of Research Excellence in Translating Nutritional Science to Good Health University of Adelaide, Adelaide, South Australia, Australia
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Ullrich SS, Fitzgerald PC, Nkamba I, Steinert RE, Horowitz M, Feinle-Bisset C. Intragastric Lysine Lowers the Circulating Glucose and Insulin Responses to a Mixed-Nutrient Drink without Slowing Gastric Emptying in Healthy Adults. J Nutr 2017; 147:1275-1281. [PMID: 28592515 DOI: 10.3945/jn.117.252213] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 04/28/2017] [Accepted: 05/11/2017] [Indexed: 02/05/2023] Open
Abstract
Background: Lysine is reported to lower the glycemic response to oral glucose in humans and, albeit at high loads, to slow gastric emptying of glucose and decrease food intake in rats.Objective: We investigated the effects of intragastrically administered lysine on early (15 min) and later (60 min) blood glucose and insulin responses to and gastric emptying of a mixed-nutrient drink, and effects on subsequent energy intake.Methods: Twelve healthy volunteers (7 men and 5 women; mean ± SEM age: 24 ± 2 y) received intragastric infusions (200 mL) containing 5 or 10 g l-lysine or a control solution within 2 min on 3 different occasions in randomized order. Fifteen minutes later, participants consumed a mixed-nutrient drink (300 mL, 400 kcal, and 56 g carbohydrates) within 1 min. For the next hour (t = 0-60 min), we collected blood samples every 15 min (to measure blood glucose, plasma insulin, and plasma glucagon) and breath samples every 5 min (to measure gastric emptying via a 13C-acetate breath test). We then quantified subjects' energy intake from a buffet-style meal (t = 60-90 min).Results: There were no differences between the 2 lysine treatments; hence, data were pooled for further analysis. Lysine did not affect blood glucose at 15 min or the blood glucose area under the curve from 0 to 60 min (AUC0-60min) but it decreased blood glucose at 60 min compared with the control solution (-9.1% ± 3.1%, P < 0.01). Similarly, the early insulin response and insulin AUC0-60min were not affected by lysine, but plasma insulin at 60 min was 20.9% ± 5.6% lower than after the control (P < 0.05). Plasma glucagon at both 15 min (20.7% ± 4.7%, P < 0.001) and 60 min (14.1% ± 5.4%, P < 0.05) and the glucagon AUC0-60min (P < 0.01) were greater after lysine than after the control. Lysine did not slow gastric emptying, and there was no effect on energy intake.Conclusion: In healthy adults, lysine slightly reduced the glycemic response to an oral mixed-macronutrient drink, an effect that was apparently independent of insulin or slowing of gastric emptying. This trial was registered at www.anzctr.orgau as 12614000837628.
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Affiliation(s)
- Sina S Ullrich
- University of Adelaide Discipline of Medicine, Adelaide, Australia; and
- National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Penelope Ce Fitzgerald
- University of Adelaide Discipline of Medicine, Adelaide, Australia; and
- National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Iris Nkamba
- University of Adelaide Discipline of Medicine, Adelaide, Australia; and
| | - Robert E Steinert
- University of Adelaide Discipline of Medicine, Adelaide, Australia; and
- National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Michael Horowitz
- University of Adelaide Discipline of Medicine, Adelaide, Australia; and
- National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Christine Feinle-Bisset
- University of Adelaide Discipline of Medicine, Adelaide, Australia; and
- National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
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Ullrich SS, Fitzgerald PC, Schober G, Steinert RE, Horowitz M, Feinle-Bisset C. Intragastric administration of leucine or isoleucine lowers the blood glucose response to a mixed-nutrient drink by different mechanisms in healthy, lean volunteers. Am J Clin Nutr 2016; 104:1274-1284. [PMID: 27655440 DOI: 10.3945/ajcn.116.140640] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 08/19/2016] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND The branched-chain amino acids leucine and isoleucine lower blood glucose after oral glucose ingestion, and the intraduodenal infusion of leucine decreases energy intake in healthy, lean men. OBJECTIVE We investigated the effects of the intragastric administration of leucine and isoleucine on the gastric emptying of, and blood glucose responses to, a physiologic mixed-macronutrient drink and subsequent energy intake. DESIGN In 2 separate studies, 12 healthy, lean subjects received on 3 separate occasions an intragastric infusion of 5 g leucine (leucine-5g) or an intragastric infusion of 10 g leucine (leucine-10g), an intragastric infusion of 5 g isoleucine (isoleucine-5g) or an intragastric infusion of 10 g isoleucine (isoleucine-10g), or a control. Fifteen minutes later, subjects consumed a mixed-nutrient drink (400 kcal, 56 g carbohydrates, 15 g protein, and 12 g fat), and gastric emptying (13C-acetate breath test) and blood glucose, plasma insulin, C-peptide, glucagon, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and cholecystokinin (leucine study only) were measured for 60 min. Immediately afterward, energy intake from a cold, buffet-style meal was assessed. RESULTS Compared with the control, leucine-10g decreased the blood glucose area under the curve (AUC) (P < 0.05) and tended to reduce peak blood glucose (P = 0.07), whereas effects of leucine-5g were NS. Leucine-10g, but not leucine-5g, increased plasma insulin and C-peptide AUCs (P < 0.01 for both), but neither dose affected glucagon, GLP-1, GIP, cholecystokinin, gastric emptying, or energy intake. Compared with the control, isoleucine-10g reduced the blood glucose AUC and peak blood glucose (P < 0.01), whereas effects of isoleucine-5g were NS. Neither load affected insulin, C-peptide, glucagon, GLP-1, or GIP. Isoleucine-10g, but not isoleucine-5g, slowed gastric emptying (P < 0.05), but gastric emptying was not correlated with the blood glucose AUC. Isoleucine did not affect energy intake. CONCLUSIONS In healthy subjects, both leucine and isoleucine reduced blood glucose in response to a mixed-nutrient drink but did not affect subsequent energy intake. The mechanisms underlying glucose lowering appear to differ; leucine stimulated insulin, whereas isoleucine acted insulin independently. These trials were registered at www.anzctr.org.au as 12613000899741 and 12614000837628.
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Affiliation(s)
- Sina S Ullrich
- Discipline of Medicine, University of Adelaide, Adelaide, Australia; and National Health and Medical Research Council of Australia Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Penelope Ce Fitzgerald
- Discipline of Medicine, University of Adelaide, Adelaide, Australia; and National Health and Medical Research Council of Australia Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Gudrun Schober
- Discipline of Medicine, University of Adelaide, Adelaide, Australia; and National Health and Medical Research Council of Australia Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Robert E Steinert
- Discipline of Medicine, University of Adelaide, Adelaide, Australia; and National Health and Medical Research Council of Australia Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Michael Horowitz
- Discipline of Medicine, University of Adelaide, Adelaide, Australia; and National Health and Medical Research Council of Australia Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Christine Feinle-Bisset
- Discipline of Medicine, University of Adelaide, Adelaide, Australia; and National Health and Medical Research Council of Australia Center of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
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12
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Steinert RE, Landrock MF, Ullrich SS, Standfield S, Otto B, Horowitz M, Feinle-Bisset C. Effects of intraduodenal infusion of the branched-chain amino acid leucine on ad libitum eating, gut motor and hormone functions, and glycemia in healthy men. Am J Clin Nutr 2015; 102:820-7. [PMID: 26289436 DOI: 10.3945/ajcn.115.114488] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 07/28/2015] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Branched-chain amino acids (BCAAs), particularly leucine, act as nutrient signals regulating protein synthesis and degradation as well as glucose metabolism. In addition, leucine has been demonstrated in animal experiments to modulate eating and energy homeostasis. OBJECTIVE We aimed to characterize the effects of physiologic and supraphysiologic loads of intraduodenal leucine on eating, gut hormone and motor functions, and blood glucose in humans. DESIGN Twelve lean men were studied on 3 occasions in a randomized, double-blind order. Antropyloroduodenal motility, plasma ghrelin, cholecystokinin, glucagon-like peptide 1, peptide YY, insulin, glucagon, blood glucose, appetite perceptions, and gastrointestinal symptoms were measured during 90-min intraduodenal infusions of leucine at 0.15 kcal/min (total 3.3 g, 13.5 kcal), 0.45 kcal/min (total 9.9 g, 40.5 kcal), or saline (control). Ad libitum eating from a buffet lunch was quantified immediately after the infusions. RESULTS Leucine at 0.45 kcal/min inhibited eating (energy intake by ∼13%, P < 0.05), increased plasma cholecystokinin, slightly reduced blood glucose and increased plasma insulin, and decreased antral pressures (all P < 0.05). Leucine at 0.15 kcal/min had no effect on food intake, blood glucose, or antral pressures but also slightly increased plasma cholecystokinin (P < 0.05). Neither dose affected plasma ghrelin, glucagon, glucagon-like peptide 1 and peptide YY, or pyloric and duodenal pressures. Plasma leucine concentrations were related to the dose of intraduodenal leucine, with substantial increases during both 0.15 and 0.45 kcal/min. CONCLUSIONS The effects of intraduodenal infusions of free leucine on eating are probably not primarily mediated by changes in gut motor and hormone functions, with perhaps the exception of cholecystokinin. Instead, increased plasma leucine concentrations may be a potential signal mediating the eating-inhibitory effect of leucine. The study was registered as a clinical trial with the Australia and New Zealand Clinical Trial Registry (www.anzctr.org.au) as ACTRN12613000899741.
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Affiliation(s)
- Robert E Steinert
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; and
| | - Maria F Landrock
- University of Adelaide Discipline of Medicine, Adelaide, Australia
| | - Sina S Ullrich
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; and
| | - Scott Standfield
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; and
| | - Bärbel Otto
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität München-Campus Innenstadt, Munich, Germany
| | - Michael Horowitz
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; and
| | - Christine Feinle-Bisset
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia, Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; and
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Ullrich SS, Otto B, Hutchison AT, Luscombe-Marsh ND, Horowitz M, Feinle-Bisset C. Comparative effects of intraduodenal protein and lipid on ghrelin, peptide YY, and leptin release in healthy men. Am J Physiol Regul Integr Comp Physiol 2015; 308:R300-4. [PMID: 25568079 DOI: 10.1152/ajpregu.00504.2014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Intraduodenal infusion of lipid or protein potently reduces subsequent energy intake. There is evidence that the underlying mechanisms differ significantly between the two nutrients. While intraduodenal lipid stimulates glucagon-like peptide-1 and CCK much more than protein, the release of insulin and glucagon is substantially greater in response to protein. Ghrelin and PYY are both involved in short-term regulation, while leptin is a long-term regulator, of energy balance; the acute effects of nutrients on leptin release are unclear. We investigated the comparative effects of intraduodenal lipid and protein on plasma ghrelin, PYY, and leptin concentrations. Thirteen lean, young men received 90-min intraduodenal infusions of protein (whey hydrolysate) or lipid (long-chain triglyceride emulsion) at a rate of 3 kcal/min, or saline control, on three separate days. Blood samples were collected at baseline and regularly during infusions. Both lipid and protein potently suppressed plasma ghrelin compared with control (both P < 0.001), with no difference between them. While both lipid and protein stimulated plasma PYY (P < 0.001), the effect of lipid was substantially greater than that of protein (P < 0.001). Neither intraduodenal lipid nor protein affected plasma leptin. In conclusion, intraduodenal lipid and protein have discrepant effects on the release of PYY, but not ghrelin. When considered with our previous findings, it appears that, with the exception of ghrelin, the energy intake-suppressant effects of lipid and protein are mediated by different mechanisms.
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Affiliation(s)
- Sina S Ullrich
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Bärbel Otto
- Medizinische Klinik, Klinikum Innenstadt, University of Munich, Munich, Germany; and
| | - Amy T Hutchison
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Natalie D Luscombe-Marsh
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; Food, Nutrition and Bioproducts Flagship, Commonwealth Scientific and Industrial Research Organization, Adelaide, Australia
| | - Michael Horowitz
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia
| | - Christine Feinle-Bisset
- University of Adelaide Discipline of Medicine, Adelaide, Australia; National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia;
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